Battery systems using a thin flexible tape of electrode material have been suggested in the prior art for supplementing or replenishing the supply of electrode as the anode electrode is consumed to prolong the life of the battery. An example of a system employing an elongated tape of anode material fed from a supply reel to a take up reel is disclosed in U.S. Pat. No. 4,916,036. The anode described in this patent is supplied from an elongated tape composed of a reactive metal such as lithium wound on a reel and fed from a first chamber through a second reaction chamber containing a solution of electrolyte and cathode to a third chamber in which the tape is wound on a take up reel. The take up reel is driven by a motor under the control of a controller to advance the tape, preferably continuously, through the bath of electrolyte. A continuous fresh supply of anode material is intended to prolong the operation of the battery. Another battery system using a strip of tape containing segments of individual battery cells is taught in U.S. Pat. No. 3,494,796. In this patent each battery cell is composed of its own anode and cathode separated by a layer impregnated with electrolyte. The tape is advanced so that an external pair of collector plate's makes contact with each cell in succession. Thus only one cell at a time is connected to the terminals for heavy discharge while the other cells are held in reserve and discharge at a low level. U.S. Pat. No. 3,577,281 is yet another prior art teaching using an elongated tape coated with an anode material which is driven into a solution of electrolyte.
The commonality between these galvanic battery systems is the use a tape or strip of anode material fed from a reel primarily to supplement the availability of anode material. This is intended to provide a high energy density to weight ratio and to yield higher battery efficiency using a minimum amount of space. The storage life of the battery and its discharge capacity in all such prior art arrangements is fixed although the battery may be discharged at a variable rate over selected intervals of time according to usage.
The galvanic battery cell of the present invention is constructed to provide operator control over the introduction and replenishment of the supply of electrode material and to provide, when necessary, a supplemental supply of electrolyte to extend the storage life of the battery for an extended period. This is accomplished by using an elongated tape having segmented sections of electrode material to provide discrete periods of operation with indefinite periods of dormancy during which the battery remains inactive. In a preferred embodiment of the invention battery operation is initiated by controlling the introduction of the anode to the electrolyte compartment of the battery housing using a strip of inactive material connected to the elongated tape in the form of a leader. The leader permits the tape containing the sections of anode material to be introduced into the electrolyte under the control of the operator. Accordingly, the battery does not begin to discharge until the battery is actually placed in use which substantially increases the storage life of the battery. In the preferred embodiment of the invention the leader performs the dual function of initiating battery operation and separating the spent anode tape electrode from the fresh anode tape.
The battery of the present invention also provides for a period of controlled dormancy between the introduction of each of the segmented sections of anode material into the electrolyte compartment thereby extending battery operation for an indefinite time period under the control of the operator.
Moreover in accordance with the preferred embodiment of the present invention the housing of the battery is constructed with only two compartments one of which is "electrochemically active" and the other of which is "electrochemically inactive". An electrochemical reaction between the anode, cathode and electrolyte occurs in the "electrochemically active" compartment. The "electrochemically inactive" compartment contains a supply of anode material which is fed to the electrochemically active compartment to operate the battery. The anode material is supplied from an elongated strip of tape which is preferably interconnected to form an endless loop. The tape also contains a strip of inactive material arranged within the endless loop to function as a leader for the tape to control activation of the battery at the outset of battery operation. Unused or spent anode material from the electrochemically active compartment is returned to the inactive compartment where it is wound on a common spool with the tape of fresh anode material using the leader of inactive material to separate the fresh anode material from the spent anode. This simplified construction permits the battery cell configuration of the present invention to be light in weight and to exhibit a higher performance efficiency and a higher energy density to weight ratio relative to any known prior art battery construction of comparable size and capacity.